(NECN) - Boston's Allston neighborhood over the weekend. They say careless disposal of smoking material caused the Sunday morning fire that ended up killing a Boston University student.

The owner of that building was also cited this week for several violations after officials found more 19 people living in a home meant for two families.

The Boston Fire Investigation Unit determined the fire started in the area of an interior staircase that was permanently blocked off on the first floor but was an open space to those using the stairs to the second floor from the rear of the house.